How to test if an img tag points to an existing image?

I'm using Cucumber and Capybara for BDD on a RoR application. I have the following feature

Feature: List profiles
In order to know that the people behind the profiles are real people
As a lurker
I want to be able to find who is registed and see their profile picture
Background: Profiles have been added to the database, some with picture attached
Given some profiles exist
And I am on the home page
Scenario: Search by city, avatars should be there
When I search for a city with profiles
Then I should see some result profiles with avatar

The underlying Capybara steps file contains:

Then /^I should see some result profiles with avatar$/ do
page.should have_css("#profile_search_results .profile img.avatar", :count => some_profiles)
end

This step checks that the page contains

<div id="#profile_search_results>
<img class="avatar" src="" />

BUT... I also want to check if the image exists (it is not a broken image).

How can I do this in my Capybara steps?

Answers

The way to check, without having to use Selenium or any other drivers, was to extract the src attribute from the img element (Thanks MrDanA), and check the status code after visiting that URL: